A study of chemically decontaminating polymers for pesticide protective clothing

Most traditional protective clothing was made of barrier materials imposing heat stress on wearers. Breathable textile materials combined with detoxifying properties, such as chemically decontaminating polymers, would be desirable for preparing comfortable protective clothing. N-halamine grafted polymers have been successfully employed as regenerable anti-bacterial textile materials to remove microbial contaminants. They are also one of the hopeful candidates of chemically decontaminating polymers for removing pesticide contaminants because of the strong oxidative ability of active halamine functional groups. Carbamate pesticides and organophosphorus pesticides were selected in this study since they are the two important classes of agricultural chemicals widely used in the world. Halamine structures incorporated on polyester/cotton fabrics were able to eliminate some selected oxime carbamate and organophosphorus pesticides that contain thio bonds rapidly upon contact. The reaction was endothermic, and the degradation rate was in first order to the concentrations of the pesticides. Due to the different structures, aldicarb was degraded in a much faster rate than methomyl by the halamine fabrics. The degradation rate of methyl parathion was also faster than that of malathion. The activation energy of imide halamine reacting with aldicarb and methyl parathion was in a range of 18-20 kcal/mol and 5.5-7.4 kcal/mole respectively. This small range of activation energy means that the degradation reaction was easy and rapid. The reactivity also depends on halamine structures since imide/amide halamine was more reactive than amine halamine. Due to the oxidation products which were identified by the mass spectrometer, the detoxification of thio-carbamates/thio-containing organphosphorus was found to be an oxidative reaction on the sulfur atom, existing in aldicarb, methomyl, methyl parathion and malathion. The oxidative products from aldicarb and methomyl are less toxic than the parent pesticides, but the oxon products are more toxic than the parent pesticides. The same halamine structures were unable to effectively react with carbaryl and carbofuran, which are aromatic carbamtes and do not contain any thio bonds. This research demonstrated that N-halamine grafted polymers were effective as regenerable chemically decontaminating textile materials based on oxidative detoxification mechanisms, but further modification is needed to decontaminate broad-spectrum contaminants.